{"id":33839,"date":"2023-09-23T08:00:00","date_gmt":"2023-09-23T06:00:00","guid":{"rendered":"http:\/\/587a66cf-aed3-4321-9862-f3b5855cddbf"},"modified":"2023-09-23T08:46:14","modified_gmt":"2023-09-23T06:46:14","slug":"asteroid-bennu-could-shatter-earth-heres-how-sundays-osiris-rex-mission-will-stop-it","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/asteroid-bennu-could-shatter-earth-heres-how-sundays-osiris-rex-mission-will-stop-it\/","title":{"rendered":"Asteroid Bennu could shatter Earth. Here\u2019s how Sunday\u2019s OSIRIS-REx mission will stop it"},"content":{"rendered":"

There\u2019s a higher chance of the asteroid striking the Earth than you finding a four-leaf clover. Scientists have 160 years to deflect it. <\/p>

By Noa Leach\n <\/p>

Published: Saturday, 23 September 2023 at 06:00 AM<\/p>

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This Sunday 24 September, NASA scientists will collect a 1kg sample of space dust and pebbles<\/a> that will parachute down from an asteroid to the Great Salt Lake Desert in Utah, USA.<\/p>

The sample has been travelling 28,000 mph (7,778 km\/h) for three years since it was collected from the asteroid known as Bennu. This is the most anticipated moment in NASA\u2019s catchily named Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx<\/a>) mission.<\/p>

Bennu is dubbed \u2018the world\u2019s most hazardous asteroid\u2019 due to it having the highest score on the Palermo Technical Impact Hazard Scale<\/a>.<\/p>

That\u2019s because exactly 159 years later to the day, Bennu may strike the Earth with so much force that continents could divide.<\/p>

The risk of this happening is 1 in 2,700<\/a>. This risk sounds low (and is \u2013 given it was initially calculated at 1 in 1,750). But it is almost twice as likely as someone finding a four-leaf clover (1 in 5,000), or over five times as likely as someone being struck by lightning<\/a> (1 in 15,300).<\/p>

Being only one-twentieth of the size of the Earth-striking asteroid that killed the dinosaurs<\/a>, Bennu would not destroy the Earth or even the life on it. However, the asteroid would leave a crater four miles (6.4 km) wide<\/a> and knock down nearby cities.<\/p>

A collision course with Earth<\/strong><\/h2>

The OSIRIS-REx mission launched in 2016 on a seven-year mission to collect the asteroid sample. The six-second process took place in 2020, before the spacecraft started its return journey to Earth.<\/p>

Already, early analysis has provided some insight into the asteroid\u2019s trajectory. Bennu is due to make its next close flyby of Earth in just over a century, in 2135.<\/p>

Terrifyingly, this flyby could put Bennu on a collision course with the Earth because of our planet\u2019s gravitational pull<\/a>. Initially, scientists calculated that Bennu could pass through 26 \u2018gravitational keyholes\u2019 on its path \u2013 any one of which could drag its trajectory in line with the Earth.<\/p>

If this happens, Bennu has the greatest chance of smashing into Earth on September 24, 2182: almost exactly 159 years from now.<\/p>

However, in 2021, NASA announced that only two of these keyholes remained viable after initial data analysis.<\/p>

View of asteroid Bennu from the OSIRIS-REx spacecraft – Image credit: NASA<\/figcaption><\/figure>

How to change the path of an asteroid<\/h2>

Sunday\u2019s sample could improve projections of Bennu\u2019s trajectory even more. \u201cWe need to understand exactly the composition of such asteroids if we are to deflect them out of harm\u2019s way in the future,\u201d Dr Darren Baskill<\/a>, astronomer lecturer at the University of Sussex, told BBC Science Focus<\/em>.<\/p>

But it won\u2019t be until 2135 that we know for certain.<\/p>

\u201cAsteroids are notoriously difficult to predict when it comes to what will happen exactly in the future,\u201d said Baskill. \u201cAn analogy is hitting a long pot in snooker \u2013 will the ball go straight in the pocket or rattle in the jaws?\u201d<\/p>

According to Baskill, asteroids \u2013 unlike snooker balls \u2013 can also be affected by solar wind. \u201cThe Sun frequently ‘burps’ gas into space, and these can ever so slightly affect the orbit of an asteroid making it incredibly difficult to say what will happen with certainty centuries ahead of time.\u201d<\/p>

In 2135, if things don\u2019t look good for Earth, scientists will have just under 50 years to deflect the asteroid. In 2022, NASA successfully trialled such a feat within its Double Asteroid Redirection Test (DART<\/a>) mission.<\/p>

\u201cThat\u2019s feasible in a 50-year time frame,\u201d said planetary scientist Lindley Johnson of NASA\u2019s Planetary Defense Coordination Office during the announcement in 2021 \u2013 especially when ac\u00adcounting for technology advances.<\/p>

He added: \u201cI don\u2019t think we need to do anything about Bennu.\u201d<\/p>

Excitingly, scientists hope that the samples will also help us understand how the solar system<\/a> and Earth formed. While it\u2019s unlikely, they could also contain biological material \u2013 signalling signs of live elsewhere in the solar system.<\/p>

About our expert<\/strong><\/h3>

Dr Darren Baskill is an outreach officer and lecturer in the department of physics and astronomy at the University of Sussex. He previously lectured at the Royal Observatory Greenwich, where he also initiated the annual Astronomy Photographer of the Year competition.<\/p>

Read more:<\/strong><\/p>